


there is thunder in our hearts

by evvianas6



Category: Avatar: The Last Airbender
Genre: Alternate Universe - Modern Setting, Alternate Universe - Superheroes/Superpowers, Canon-Typical Violence, Eventual Romance, F/M, Mutual Pining, superhero au is a classic zutara trope and one that i am happy to write for
Language: English
Status: Completed
Published: 2018-11-13
Updated: 2018-11-24
Packaged: 2019-08-21 19:09:54
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,683
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16582364
Author URL: https://archiveofourown.org/users/evvianas6/pseuds/evvianas6
Summary: Katara never would have chosen this life-late nights, her new strange powers, hunting down criminals in the streets of Republic City-until it meant spending more and more time with a man in a Blue Spirit mask.





	1. hero of this story

Katara could never tell when it would come-that heavy pressure at the base of her spine, demanding come find me. Usually it happened at night, waking her from sleep to run through the city until she found what she was looking for, but sometimes, just like today, it happened during a lecture and she was forced to make her excuses before rushing off.

The mask was another one of her new, strange instincts. She’d bought it on a whim at a street market a few months ago, taken with the elegant red-on-white designs, but now it hid all her vigilante activities. Katara tugged it on as she ran across campus, praying to all the gods above that no one would see her.

The pressure abated somewhat as she neared the Dragon Flats, and she slowed, trying to take stock of the situation. The apartments that lined the street were run-down and falling apart, but she couldn’t hear the usual screaming that came alongside things like this. 

Then Katara rounded a corner to see a man with a knife and a woman shakily handing over her purse. 

A mugging? Seriously, she had to skip the Bio lecture for this?

She approached carefully, not wanting to alert the mugger to her presence. Energy pooled in the pit of her stomach, and her fingers twitched, just waiting for the outpouring of power that was soon to follow. Mentally, Katara searched for a water source in the alley, turning up nothing until she found the rainwater sewer below her feet. Perfect. 

“That’s all I have!” the woman pleaded, thrusting her purse at the man. “Please!”

The man shook his hand. “Not good enough,” 

The silver of his knife glinted in the afternoon sun, thrusting out until a well-timed water whip sent it out of his hand and clattering to the concrete below. 

“What the hell?” the man said, turning around. He caught sight of Katara, and glared at her. “The Painted Lady. Should have known.”

Katara winced. After a few months of essentially being a vigilante, the news had caught wind of her. Or more accurately, caught wind of the Painted Lady, the name they had given her, based on the Fire Nation spirit her mask was designed after. 

She might have said something, but the man was coming closer, so she did the only thing left to do. Katara seized the water that had puddled on the concrete and swept his legs out from underneath him. 

Well, that was what she tried to do, and she might have been successful save for the shadow that jumped between her and the man, and in one swift movement, shot bright fire out at him. 

Katara blinked, feeling a little slow on the uptake. Understanding that she herself possessed some sort of power the universe had seen fit to have given her was one thing, but knowing there was another person out there just like her? She was going to need some time to wrap her head around that. 

The man ducked to avoid the blaze, and Katara’s instincts screamed at her. Water swelled up from the concrete and the sewer, freezing around his hands and feet and tethering him to the ground.

A moment later, the woman ran past the two of them, frantically dialing 9-1-1 on her cell phone. 

The shadow turned towards her, and Katara realized he was a man, his face hidden by a sculpted blue demon’s mask-the kind they used in theatre. He wore all black, but it didn’t hide his muscular form. Heat flushed in Katara’s cheeks, and she was suddenly very thankful for the mask she was wearing. 

“Who are you?” she demanded, stepping closer and shaking those thoughts out of her head. The man had almost an extra foot on her, but she didn’t care. Another vigilante in Republic City? She wanted answers.

“You can call me the Blue Spirit,” he said, his voice measured and mellifluous, but with a strange rasping quality that made her wonder when the last time he had talked to someone was. 

“Great, that answers all my questions!” Katara laughed sarcastically, and glared at him. 

The Blue Spirit held up his hands in defence. “Hey, I’ve got questions too. You’re the Painted Lady, right?”

“Oh, now even the mysterious ‘Blue Spirit’ knows about me. That’s just fantastic.” 

If the Blue Spirit noticed the bite to her words, he didn’t let on. “I saw you on the news. I thought you were just some wannabe superhero, or a copycat neighbourhood watch team or something. I didn’t-I didn’t think there was someone else out there like me.”

Katara crossed her arms. “Well, I’ve never heard of you.”

The Blue Spirit shrugged. “This-” and he gestured back to the mugger frozen to the ground. “Only started for me a few weeks ago.”

She opened her mouth, about to say something, and paused. Frozen like he was, the mugger posed no threat to the two of them, but if the woman had called the cops they’d be here soon, and they probably wouldn’t take to kindly to a pair of wannabe vigilantes. 

“I think it might be a good idea to continue this conversation elsewhere,” she said, pointing her head towards the mugger. 

The Blue Spirit nodded. “Good idea. Follow me, I know a place.”

He turned to leave the alley. Katara glared at his back, a sharp retort rising on her lips, but she choked it down at the last minute. It probably wasn’t worth it to antagonize this guy, at least not before she got her answers. 

The Blue Spirit moved carefully, always ducking into shadows and alleyways when people walked by. But that also meant they were walking at a snail’s pace. 

“How much longer is this going to take?” she asked, only for the Blue Spirit to turn back and shush her.

“We’re almost there,” he whispered. Katara rolled her eyes, but true enough, it wasn’t long before he turned down an alleyway and pointed at a rusty fire escape. “My apartment’s up there.” 

She rolled her eyes again, but of course he couldn’t see it with her mask on. “If you say so,” she said, hoping to convey the disdain she felt. 

The Blue Spirit didn’t respond. In one smooth movement he jumped up to the lower rungs and swung himself over the side of the fire escape. A moment later he had the apartment door unlocked.

Well. Two could certainly play at that game. 

Katara backed up, judging the distance from the ground to the ladder, and took a running leap. She caught the lowest rung easily, and hauled herself up as gracefully as she could manage. 

The Blue Spirit nodded curtly, and shut the door behind her.

A few months ago, Katara would’ve been worried about being in an apartment with a man she barely knew, but now she figured she’d be able to take him if it came down to a fight.

The apartment itself was a lot nicer than she was expecting. It was still run-down, and in a bad neighbourhood, but it was clean, and posters and knicknacks lining the walls gave it a nice personal touch. 

The Blue Spirit sat down on his couch, and motioned for Katara to join him. She did, a little hesitantly, and then he spread his hands in surrender. 

“You said you wanted to talk, so let’s talk.”

“Right,” she said, trying to get her thoughts in order. “You said this started a couple weeks ago for you?”

He nodded. “Yeah, pretty much. I stopped a robbery, and realized I had whatever this is.” He waved his hand, fire sparking to life in his palm. Katara flinched, but quickly realized he had it in control. It was kind of disconcerting, talking to someone when you couldn’t even see his face, but Katara wasn’t about to reveal her identity, and figured he felt the same. 

“And you’ve no idea why this happened?”

The Blue Spirit shook his head. “No clue.”

Katara frowned. So the Universe had decided to give two random people superpowers so they could stop petty crime? That didn’t make sense. 

“Sorry I can’t be of more help,” The Blue Spirit said, and hesitated, like he wanted to say something else. “Do you . . . want some tea?”

She blinked. “Tea?”

“Yeah, I’ve got ginseng, oolong, jasmine . . .” he trailed off, rubbing the back of his neck. “Unless you don’t want any! That’s okay too.”

“Thanks but I have to get back to class,” Katara said, and for some reason, couldn’t help feeling a little disappointed. 

“Oh, alright,” The Blue Spirit said, and Katara imagined that he was disappointed too. Then she mentally scolded herself to stop being silly. 

Still, on her way out, she couldn’t help but wish that he’d asked her to stay.


	2. warrior blood

Zuko ducked under a vicious right hook and tried to focus. Figured that the Universe had decided it was time for him to break up a triad fight all by himself, especially after he was reeling from his meeting with the Painted Lady. 

Azula would’ve teased him about being love-struck, but that was not true at all. There was nothing wrong with being interested in a fellow vigilante/superhero, even if she was fierce and uncompromising and probably beautiful under that mask . . .

And now he was getting distracted again. He leapt out of the path of a dagger, and tossed fire back at the man who’d tried to stab him. 

One of the gang members swore, backing away from him, and Zuko took the opportunity to catch his breath before the fight started again in earnest. He had managed to stay out of the news so far, but that would probably end tonight.

Oh, well. He used the Blue Spirit mask for a reason. 

A triad member was getting too close for comfort. Zuko threw a couple of punches, fire following moments later to keep her off-guard, ducked, and swept the leg. She fell to the concrete, and he turned just in time to block a sharp kick to the face. 

Zuko took a deep breath, and let the pure instinctiveness of a good, hard fight wash over him. Every movement was smooth, every attack met its mark. He could forget everything in moments like these-it was almost like the meditations Uncle tried to get him to do. 

Of course, when all the triad members were either unconscious or injured on the ground and he’d called the police, he still had all his usual worries left to deal with.

Like: he hadn’t seen the Painted Lady in over a week or even heard about her exploits. Sure, maybe she was just trying to lay low, and she didn’t seem to like him that much, but he would’ve wanted to find out everything he could about someone else with superpowers, even if it was someone like Azula. Or: he was pretty sure he was going to miss rent this month, because he kept skipping out on his shifts and dishing out vigilante justice didn’t come with a paycheck. 

Or: most pressingly, the giant black-spirit? demon? ghost?-thing rising out of the street in front of him. It hovered in the air for a moment, before it glowed a furious dark red and flew at him. 

Zuko rolled out of the way, narrowly avoiding being crushed by the spirit. Fire bloomed to life in his hands as he turned back to fight.

The spirit pulsated, almost like it was mocking him, but it didn’t get to do more than that before Zuko sent a blaze of fire straight through its heart. 

It crumpled around the wound like wet paper, hissing and wheezing as it collapsed to the ground. Zuko was reminded somewhat of a fish out of water, flopping around until it finally gave up, the rest of its body oozing between the cracks in the street.

He grimaced. The fight had been easier than he’d expected, but a spirit? Those were supposed to be legends, not real things you could fight. Certainly not real things you could blast apart with fire in an alleyway. 

But he couldn’t deny the fact that an angry spirit had attacked him and he had won, just like he couldn’t deny the fact that the Universe had decided to give him fire powers so he could fight crime. Zuko sighed. It sounded so silly when he put it like that.

Then he remembered-if a spirit wanted to attack him, it might want to attack the Painted Lady. 

That familiar pressure started in his bones, as if in response to the thought. Zuko tightened the straps of his mask where they had come loose in the fight, and started to run.

 

He found her pretty quickly, hurrying along Liao Street. 

“Hey!” Zuko called out, and regretted it immediately. The Painted Lady whipped around, water already collecting along her hands, but she stopped when she saw it was him.

“You again,” she said, letting the water drop back to the ground, though her tone was still sharp. “Are you stalking me or something?”

“No-I, uh, I got attacked.”

Zuko couldn’t see her face, but he imagined that she was raising an eyebrow is disdain. “And you had to tell me this . . . why?”

“Because it was a spirit.” 

“A spirit? Those aren’t real, you know.” 

Zuko took a deep breath. “This one was. It attacked me a couple streets over, right after I broke up a triad fight. I managed to kill it.”

“What? Was it a dark spirit?” she asked insistently. “Tell me you didn’t kill a dark spirit.”

Zuko thought back. “Well it was kind of black and red, so I guess it was a dark spirit. Why? What’s going to happen?”

But she was only shaking her head, pushing past him. “All the legends say that dark spirits are corrupted versions of their true forms. If you kill them, that corruption just seeps right back into the city.”

What? That made no sense. How else were you supposed to get rid of them? 

He voiced the thought, and she sighed. 

“You’re supposed to heal them, not fight them.” she said, and turned back to him. “Where did it attack you?”

“Over on Tao, but I just busted up a triad. Cops are probably swarming the area.” 

“Oh, that’s just great-” she said, only to be cut off by the sight of a colossal dark spirit rising from the cobblestones, pulsing in anger.

“Shit!” Zuko swore, moving to stand in front of the Painted Lady. Of course, that was a pretty stupid move, since she immediately pushed past him, water rising in her hands. 

She lifted a cone of water around the spirit, hands shaking in concentration. What was she doing? There was no way the spirit wouldn’t be able to push through that. 

But just as the water surrounded the spirit in a bubble, it started to glow a brilliant blue, the colour leaching away the black. 

Zuko couldn’t believe his eyes. The Painted Lady was purifying the dark spirit. He’d never even know that that was possible. 

Slowly, gently, the spirit shuddered, transforming into tiny lights and drifting away in the wind. It was one of the most beautiful things he’d ever seen. 

Then the Painted Lady collapsed into his arms, the healing water she’d used crashing back onto the street. She was breathing, but shallowly. 

Zuko’s fingers tugged at the straps around her mask, pulling it from her face to help her breathe. He pulled her to the side of the street, settling her down with her head in his lap, since she was still asleep. 

He had no idea what to do in this kind of situation. What was he supposed to do, call an ambulance and tell them a girl he barely knew collapsed after healing a dark spirit? No way. He could bring her back to his apartment, but he wasn’t sure he could carry her.

But just as he was bordering on the edge of panic, her eyes fluttered open.

“What . . . what’s happening?” she murmured, brushing a lock of dark hair out of her eyes. She was Water Tribe, he noticed, with bright blue eyes and smooth brown skin, and really, unsurprisingly beautiful.

“We were attacked by a dark spirit, and you healed it.” Zuko said, and her eyes widened. 

“Really?” she said, moving up into a sitting position and rubbing the back of her head. “Ow.” 

“Are you okay?” he asked, helping her stand up. “I could . . . walk you home if you want?”

“Sure, why not?” she said, and laughed. “I mean, I already know where you live, so now it’s fair.”

“Oh!” Zuko said, fumbling with the Painted Lady mask as he handed it back to her. “I took it off, to help you breathe. So here.”

She raised an eyebrow, but instead of tying it back around her head, she just slipped it into her bag and started walking. He hurried to catch up with her, berating himself to not get distracted by the cascade of her dark curls, or the way her skin glimmered in the moonlight, or how she walked like a dancer.

“So do you think the spirit will come back?” Zuko asked, and the Painted Lady frowned. 

“That one won’t,” she said. God, she walked fast. “But if a spirit went dark, it’s probably a deeper issue in Republic City that affected it. Like pollution, or increased crime, or even a corrupt politician.”

Zuko nodded. “Right,” he said, trying to think. Republic City was always growing, always at the forefront of development in the world, and the crime rate always grew with it. What wouldn’t anger a spirit in a city like that? Then the answer came to him. “What about that oil refinery they’re building? Up near the mountains?”

The Painted Lady turned back, her eyes lighting up as she nodded. “Right! The construction must be interrupting the spiritual activity. I bet if we got up there we’d see a ton of dark spirits.”

“Could you heal that many?” he asked.

“Maybe I wouldn’t have to,” she said, and he could almost see the gears turning in her mind. “If we could locate the spiritual epicenter and purify that, it’d probably stop the attacks before they get out of hand.” 

“Then what are we waiting for?” Zuko said, as the Painted Lady slipped her mask back on. “Let’s go.”


	3. we're gonna be legends

The oil refinery was nestled into the foothills at the base of the mountain, safe and satisfied with it’s vantage point over the city. Of course, it had been designed in mind of keeping out corporate spies, not two super-powered vigilantes, so Katara and the Blue Spirit found their way in easily. 

She dropped down from the chain-link fence into a supply yard, and almost gagged. The place stank of spiritual darkness, and she would have stumbled, save for the Blue Spirit catching her arm.

“Are you alright?” he asked, steadying her. “I can feel it too.”

Katara took a deep breath and nodded tightly. “I’m fine. And it’ll be easier to find the spirits if we can sense their energy.”

“Long as you’re sure,” he said, and they were off again. 

The only security at the refinery were a handful of rotating night guards, easy for them to avoid as they made their way through the building. The dark energy only increased as they descended below the earth, and the clanking machinery and oppressive heat made Katara feel like she was trapped in some sort of dark underworld, half-expecting a spirit to pop out at every turn. 

She found herself wishing she could tie her hair back with something, just to get it off the back of her neck. How was it that they had been down here for so long, forced to breathe in smoke and oil and spirit stink, but hadn’t actually seen a single real spirit?

The Blue Spirit muttered something that sounded suspiciously like ‘this is a waste of time’, just before a pair of dark purple spirits swarmed out of the wall in front of them, glowing a hostile crimson. 

“Oh, shit,” she swore, pushing past the Blue Spirit, the water from her skin already pooling in her hands. She had to get them contained before they started attacking, or risk bringing the whole refinery down on their heads. 

Katara moved as quickly as she could, trembling in concentration as she encircled the spirits with water, letting the energy pooling in the pit of her stomach rush out into the water she controlled. It started to glow that brilliant blue-white, dissolving the spirits into light. So close, just a little bit further-

Until the spirits charged through the water like it was nothing and disappeared into the wall above their heads.

“Um . . . what was that?” The Blue Spirit asked. Katara couldn’t see his face, of course, but fear coloured his voice.

“Nothing good,” she answered, staring at the space where the spirits had vanished. “It means they’re getting stronger. We need to find the epicenter before they overrun the facility.”

He nodded firmly, and they plunged deeper into the refinery.

 

Now every one of Katara’s senses was on high alert, searching for the spirits she knew might be lurking just behind the metal walls. Every stray noise made her flinch, certain they were about to be attacked, but their journey into the depths of the refinery went unchallenged. 

Until they reached a platform overlooking a deep cavern carved into the earth, absolutely crawling with dark spirits. Katara gasped despite herself, and nearly stumbled to her knees under the spiritual onslaught.

“Think you can purify this?” The Blue Spirit said, guiding her back to her feet.

“I have to try,” Katara whispered, and gathered what little water she had left. 

At first, the spirits didn’t notice the glowing tendrils of water encircling their territory, slowly healing the black and red glow emanating from the center of the cavern. She moved as fast as she dared, putting every ounce of energy and power she possessed to the task. 

Then, almost as if they were acting as one, the spirits started to swarm and writhe, flying towards her. Katara faltered, water falling from her grasp, but then the Blue Spirit was throwing fire, not letting a single spirit breach the gap between them.

She began again with renewed vigour, trusting the Blue Spirit to watch her back as she worked. They moved in tandem-he blasted spirits away from her, and she caught them in her grasp to heal. The air filled with the light from the purified spirits, the hostile energy beginning to ease. Hope soared in her heart, that maybe, just this once, she’d be able to win, to save the day. 

When the last spirit transformed into light, she turned to the Blue Spirit, lifting up her mask to beam at him. 

“We did it,” he said, and Katara could tell he was smiling underneath his mask. 

“We really did,” she said, and she wanted to throw her arms around him and dance. “We won!” 

Unable to resist any longer, Katara hugged him, but he stiffened under her touch. She stepped back, afraid she had offended him, but he was staring at something just behind her. 

She turned, and felt the blood drain from her face. 

The biggest spirit she had ever seen was rising from the cavernous depths of the refinery. She could sense the hatred and anger radiating from it, as clearly as she could see the intricate red and black patterns that adorned it. But what was even worse was the lightning crackling around it, like it had absorbed the electricity from the refinery. 

The spirit reared up above them, and something told her it was about to charge.

“No!” Katara screamed at the spirit, but it didn’t even sound like her own voice. And then it flew at the Blue Spirit, lightning rushing towards him as he crashed into the far wall, slumping over unconscious. 

She roared at the spirit, blasting it with water and forcing it back towards the canyon edge. The water glowed, and she wasn’t even trying, rage building inside her like a dam about to break. The spirit lashed out at her, sweeping lightning across the metal platform, but she ducked and weaved, never allowing it to hit her. Like it had hit the Blue Spirit.

Katara fought like she had never fought before, moving like whatever being had given her powers also controlled her limbs. There was no thought or worry, only simple attack and block, offense and defense. Her mask slipped off her face, but she didn’t care. 

When the spirit finally collapsed into the cavern, drifting away in tiny specks of golden light, she scarcely noticed save for a sudden lightness in her limbs. Then she remembered the Blue Spirit. 

Katara rushed to his side, pushing aside his mask to help him breathe (like he had done for her), fingers scrambling to lift the frayed fabric of his shirt away from his wound. 

She sucked in a deep breath, staring at the injury. It was if the lightning had nearly torn through him, and she had no idea if she could help, or even how to. But whatever had helped her fight the spirit was moving her arms again, pulling water against the Blue Spirit’s wound and making it glow. Before her very eyes, the skin below her hands started to knit back together. 

The Blue Spirit will have a scar across his chest for the rest of his life, but he will live. Still, Katara only relaxed when his breathing started to come easy and his golden eyes flickered open. A dark burn scar twisted across his left eye, and the glowing water in her hands started to drift towards it, but then he was looking at her and smiling and trying to sit up.

“Painted . . . Lady,” he coughed, and happy tears welled up in Katara’s eyes.

“Please,” she said. “My name is Katara.” 

He blinked at her, caught by surprise. Then he relaxed, and grinned at her. “It’s nice to meet you, Katara. My name is Zuko.”

“Zuko,” Katara repeated. The name felt solid and strong in her mouth, just like the man it belonged to. “How are you feeling?”

Zuko groaned. “Like I was thrown into a wall. But not like I was struck by lightning, which I guess is your doing.”

Katara blushed, inexplicably, and cursed the fact that she had no mask to hide her face. “Uh, yeah. I healed you, I guess.” 

His gaze softened. “Thank you, Katara. I don’t know what I’d have done without you.” Then the corner of his mouth lifted in a wry smile. “Gotten my ass kicked, probably.”

She laughed despite herself, and hugged him tightly. For a moment he stiffened, but quickly relaxed under her touch. “I just . . .” she murmured, trying to put her thoughts into words. “I’m just glad you’re okay.”

“Me too,” Zuko said, and hesitated, like he wanted to say something else. “I’m glad I met you, Katara.”

She smiled, and before she could talk herself out of it, she leaned over and kissed him. He jerked back in surprise, and she broke away, mentally berating herself the whole time. Of course Zuko didn’t want to kiss her-he barely knew her. 

“I’m sorry,” Katara apologized, but Zuko was smiling. 

“No, no-I, uh, I liked it. I . . . I like you, Katara.” 

“Oh,” Katara said, caught by surprise, but then Zuko kissed her. She kissed back, and how right the world was then. His skin was hot, and she found her hands entwined in his hair, but she broke away after a few moments. “We should probably get out of here,” she said, gesturing to the refinery around them.

Zuko chuckled. “Yeah, that’s probably a good idea.”

Then the Blue Spirit took the Painted Lady’s hand, or the Painted Lady took the Blue Spirit’s, and together they made their way back up into the world.

**Author's Note:**

> Come say hi to me on [tumblr!](zukos-katara.tumblr.com)


End file.
